1. Field of the Invention
This invention relates to traffic safety devices and, more specifically, sign stands.
2. Description of the Related Art
Sign stands are used for numerous purposes, such as warning about traffic conditions, announcing work areas, posting speed limits, delineating traffic and the like. The signs mounted to the sign stands may reach four feet in diameter. The signs may also be mounted on permanent or transportable sign stands with the bottom of the sign being seven feet or more above the ground.
When using the sign stands outside, they are subjected to wind and vacuums created by passing vehicles. The sign acts as a sail and catches the wind. If the sign stand were rigid, the wind on the sign would create enormous forces against the stand.
The prior art discloses sign stands that permit the wind to spill off of the sign. An example of such a sign stand is disclosed in U.S. Pat. No. 4,498,657 to Werner entitled xe2x80x9cSign Standard For Supporting And Displaying A Sign,xe2x80x9d which is incorporated herein by reference in its entirety. Werner discloses a rigid mast that is interrupted by a spring assembly. The prior art also discloses inserting a spring assembly between the rigid mast and the bottom support or base. In either case, the spring assembly flexes to permit wind to spill off of the sign mounted on the rigid mast. By being able to spill the wind, the sign stand may be smaller, lighter, easier to handle and transport than a similar stand designed to withstand the wind.
The sign stands are often hit by errant vehicles and need to be designed to withstand sufficiently the impact. Ideally, the sign stand withstands sufficiently the impact if it may be simply and cost effectively repaired and placed back into service.
When a sign stand is impacted by an errant vehicle, the rigid mast of the sign stand severs typically at the bottom of the mast. The impact and severing of the mast results in the mast incurring a polar momentum with the top of the rigid mast rotating down toward the vehicle with a great force. The combination of the downwardly rotating rigid mast top and the moving vehicle may result in the mast top piercing the windshield and injuring passengers in the vehicle.
In the Fall 1998 issue of SIGNAL, which is a biannual publication of the American Traffic Safety Services Association (ATSSA), it is reported that existing portable sign systems have not been accepted by FHWA""s Office of Engineering. The ATSSA has stated that it is paramount that the traffic safety industry works toward acceptable portable sign systems. To be accepted by the FHWA""s Office of Engineering, sign stand parts do not penetrate the occupant compartment of the errant vehicle that strikes the sign stand.
Thus, there is a need for a sign stand that has a mast with a reduced chance of piercing a windshield after being struck by a vehicle.
In an aspect of the invention, a sign stand has a mast with a flexible upper portion. In a further aspect of the invention, at least one end of a sign is mounted to the mast flexible upper portion. In a still further aspect of the invention, a top end of the mast flexible upper portion extends beyond a top edge of the sign.
Aspects of the invention may have items besides signs attached to the flexible upper portion of the mast, such as a flag holder, a light mounting bracket, a light, or sign mounting brackets.
In aspects of the invention, the sign may be comprised of metal, composite materials, or fabric. The metal sign may be comprised of aluminum.
In an aspect of the invention, a mast lower portion is connected to a support stand. In a further aspect of the invention, the mast lower portion is flexibly connected to the support stand base by the use of springs.
In an aspect of the invention, the mast is telescopic. In a further aspect of the invention, the flexible mast upper portion and the mast lower portion are in a telescopic relationship. In a still further aspect of the invention, the flexible mast upper portion telescopes from an interior space of the mast lower portion.
In another aspect of the invention, at least a portion of the flexible mast upper portion is disposed inside the mast lower portion when the mast is in the use or extended position.
In another aspect of the invention, the flexible mast upper portion and the mast lower portion are mechanically attached in the use or extended position and in the storage or collapsed position.
In an aspect of the invention, the mast comprises a rigid lower portion that defines an axis. A distally located tip of the flexible upper portion deflects from 10 to 20 inches from the axis when 16 pounds of force is applied to the tip. In a preferred aspect of the invention, the tip deflection is 10 to 15 inches when 16 pounds of force is applied. In a more preferred aspect of the invention, the tip deflects approximately 15 inches when 16 pound of force is applied. In an aspect of the invention, the tip may deflect between 10 and 20 inches when 16 pounds of force is applied to it. In other aspects of the invention, the tip may deflect 15 inches when a force of between 10 and 20 pounds is applied.
In an aspect of the invention, the flexible upper portion has a modulus of 300,000 to 400,000 psi. In a preferred aspect of the invention, the flexible upper portion has a modulus of approximately 350,000 psi.
In an aspect of the invention, the flexible upper portion comprises polyvinylchloride, polycarbonate, acrylonitrite butadiene styrene or fiber reinforced plastic. In a more preferred aspect of the invention, the flexible upper portion comprises a square tube of polyvinylchloride.
The present invention, together with additional features and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying illustrative drawings.